1. Field of the Invention
The present invention pertains to treating an earth formation in the vicinity of a wellbore by introducing an artificial matrix into void spaces in the formation together with a polymer gel to improve the consolidation or conformance of the formation and control the permeability thereof.
2. Background
In fluid production or injection wells, it is often necessary to reduce the permeability of certain portions of the earth formation in communication with the well to control the flow of fluids to or from the well. One technique which is employed to improve the conformance and reduce the permeability of earth formations in the vicinity of hydrocarbon fluid production wells is to inject a polymer type gel composition which forms a continuous single phase gel in the formation of sufficient strength and stability to effectively reduce the permeability of the formation to control flow of fluids in a desired direction or to prevent unwanted flow of fluids from certain portions of the formation.
In many instances, the formation consists of a matrix and certain anomalies. The anomaly is generally a void space in the formation having, of course, very high permeability relative to the formation matrix. Anomalies may include fractures, vugs, channels, caverns, wash-outs or cavities whereas the formation matrix is substantially the remainder of the formation volume characterized as essentially homogenous, continuous sedimentary material. In attempting to reduce the permeability of certain formation zones, the anomalies may present problems when the permeability reduction technique involves the injection of certain cross-linked polymer type gels, for example. Conventional polymer gels usually do not have sufficient strength to occupy an anomaly and resist the incursion of fluids into and through the anomaly. Since void spaces or "voids" often occur in the vicinity of perforations in a fluid production well, in order to plug these perforations or reduce the permeability of the formation in the vicinity of these perforations, filling the void with the gel and causing the gel to permeate into the natural matrix around the void space is not sufficient to provide a competent permeability reducing or plugging operation. The present invention has been developed with a view to improving the use of polymer gels and similar formation plugging or permeability altering compositions and associated processes.